Arm cortex ( lpc 2148 ) based motor speed control
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This document describes a project to control the speed of DC and AC motors using an ARM7 LPC2148 microcontroller. It uses pulse width modulation (PWM) signals from the microcontroller and motor driver circuits to vary the duty cycle and average voltage applied to the motors, allowing control of motor speed. The hardware used includes an LPC2148 board, LCD, control switches, L293D DC motor driver, optocoupler, TRIAC, and snubber circuit for the AC motor. The project successfully demonstrates controlling motor speed by varying the PWM duty cycle from 30% to 90%.
Arm cortex ( lpc 2148 ) based motor speed control
- 1. GOVERNMENT COLLEGE OF ENGINEERING, CHANDRAPUR ELECTRICAL ENGINEERING DEPARTMENT 2014-15 ARM CORTEX ( LPC 2148 ) BASED MOTOR SPEED CONTROL GUIDED BY- PROF.S.P.JOLHE PRESENTED BY 1. UDAY D. WANKAR 7. VARSHA V. HIWARE 2. GOPAL K. MOTI 8. LAKSHMI SINGH 3. PRATIK A. SAKHARKAR 9. RUPALI N. GHTUKE 4. KUNAL R. PATIL 5. SURENDRA M. BUTALE 6. VILAS J. DORLE
- 2. Introduction AC motors have been widely used for the industries since earliest days of electrical engineering. The project is designed to control the speed of a DC and AC motor using ARM7 LPC2148 processor . This project uses the PWM principle to control the speed of the motor by varying the duty cycle of the pulses applied to it known as PWM Control. The project uses the input button interfaced to the processor. A motor driver IC is interfaced to the ARM7 LPC2148 processor board for receiving PWM Signal.
- 3. HARDWARE REQUIRED Power Supply LPC 2148 Development Board LCD Control switch board L293D Driver IC Optocoupler (MOC 3021) TRIAC BT136 Snubber Circuit
- 4. Working Principle If voltage across motor terminal is varied, then speed can also be varied. This project uses the above principle to control the speed of the motor by varying the duty cycle of the pulses applied to it, popularly known as PWM control. The average voltage given or the average current flowing through the motor will change depending on the duty cycle, ON and OFF time of the pulses, so the speed of the motor will change.
- 5. Pulse Width Modulation (PWM) what is it? Output signal alternates between on and off within specified period Controls power received by a device The voltage seen by the load is directly proportional to the source voltage
- 6. Definition Duty Cycle: on-time / period Vlow is often zero LOWHIAVG VDDVV )1(
- 7. PWM signals of varying duty cycles
- 8. Block diagram of our system
- 10. ARM LPC2148 32 bit ARM7 microcontroller in a tiny LQFP64 package. 40kb of on-chip RAM. 512kb of on-chip flash memory. High speed 60 MHz operation. Two analog to digital converters(10 bit). Total 14 ADC inputs in LPC2148. 6 PWM outputs.
- 11. Pin diagram of LPC2148
- 12. Control Switches On pressing clockwise or anticlockwise button ,LPC configure output for clockwise or anticlockwise direction. On pressing low sped or high speed button motor start rotation in clockwise direction.
- 13. DC motor driver circuit L293D is a dual H-bridge motor driver integrated circuit (IC).Motor drivers act as current amplifiers since they take a low-current control signal and provide a higher-current signal.
- 14. Features: Wide supply-voltage range:4.5V to 36V Separate input-logic supply Internal ESD protection Thermal shutdown High-Noise-Immunity input Output current 1A per channel(600 mA for L293D) Output clamp diodes for inductive Transient Suppresion (L293D)
- 16. AC motor driver Ac motor driver circuit uses optoisolator MOC3021, TRIAC BT136 and snubber circuit. The process is carried out at high frequency, switching load on and OFF thereby controlling power to the load.
- 17. Optoisolator (MOC3021) Optoisolator MOC3021 is 6 pin IC & is made up of light emitting diode and DIAC which are Electrically isolated. Optoisolator allows two circuit to exchange signal yet remain electrically isolated. The light is proportional to the signal, so the signal is transferred to the photodiac. This is the principle used in opto triac and opto SCRs which are readily available in IC form. The isolation between low power and high power circuits in this optically connected device is several thousand volts. Optoisolator MOC3021 is mainly used as TRIAC driver in this project
- 18. TRIAC TRIAC is a bidirectional triode thyristor. It can be triggered by either a positive or negative voltage being applied to its gate electrode. TRIAC is allowing the control of very large power flows with mA-scale control currents for ac circuit. Applying trigger pulse at a controllable point in a AC cycle allows one to control the percentage of the current that flows through TRIAC to the load.
- 19. Snubber circuit The main function of snubber circuit is to improve the switching behavior of the TRIAC at turn off. It is often designed with a network made of a resistor R and a capacitor C, the SNUBBER circuit. This circuit can also be used to improve TRIAC immunity to fast transient voltages.
- 20. Result of DC motor Control PWM signals from LPC2148 is given to L293D which controls 12V or greater voltage by 5V dc from PWM pins. At 30% duty cycle PWM signals, DC motor runs at low speed.
- 21. At 90% duty cycle PWM signals, DC motor runs at high speed.
- 22. 50% PWM signal is given to MOC3021, DIAC in MOC3021 triggers triac gate only 50% of single pulse i.e. TRIAC is on for 50% of time. AC motor runs at lower speed. Result of AC motor Control
- 23. 90% PWM signal is given to MOC3021, DIAC in MOC3021 triggers triac gate only 90% of single pulse i.e. TRIAC is on for 90% of time. AC motor runs at higher speed.
- 24. Conclusion 1. The main aim of this project is to control the speed of motor using PWM technique by ARM processor. 2. Implementation is easy and understandable. 3. User friendly project.